docs: def load_rdf(self,
                   uri_or_path=None,
                   data=None,
                   file_obj=None,
                   rdf_format="",
                   verbose=False,
                   hide_base_schemas=True,
                   hide_implicit_types=True,
                   hide_implicit_preds=True):
          """Load an RDF source into an ontospy/rdflib graph"""
          loader = RDFLoader(verbose=verbose)
          loader.load(uri_or_path, data, file_obj, rdf_format)
          self.rdflib_graph = loader.rdflib_graph
          self.sources = loader.sources_valid
          self.sparqlHelper = SparqlHelper(self.rdflib_graph)
          self.namespaces = sorted(self.rdflib_graph.namespaces())